Digital signature schemes are known whereby cryptographic techniques are used to simulate the security properties of a signature in digital, rather than written form. Such signature schemes may be used to authenticate messages, to ensure that messages are not altered during transmission and also to reduce the likelihood that a sender will later disclaim responsibility for a message sent by that sender.
Electronic signature schemes are also known which do not necessarily use cryptographic techniques. In this case, an electronic sound, symbol, or process, is attached to or logically associated with a record and executed or adopted by an agent with the intent to sign the record. For example, such electronic signatures may include faxed copies of handwritten signatures, personal identification numbers (PIN numbers), and online signature of electronic documents.
A digital signature is considered an example of a type of electronic signature.
For all these types of signature schemes a verification process is required to enable receivers to check whether the signature was generated by the alleged sender and optionally also to check whether a message associated with the signature has been altered after signing. However, depending on the particular signature scheme being used this signature verification process differs. It is difficult to provide a mechanism that is able to verify electronic signatures of different types in a simple and cost-effective manner.